Improvement of Thermoelectric Properties in (Bi0.5Sb0.5)2Te3 Films of Nanolayered Pillar Arrays

In this work, it is found that unique pillar arrays with nanolayered structure can favorably influence the carrier and phonon transport properties of films. p-(Bi0.5Sb0.5)(2)Te-3 pillar array film with (0 1 5) orientation was successfully achieved by a simple ion-beam-assisted technique at deposition temperature of 400A degrees C, owing to the enhanced mobility of deposited atoms for more sufficient growth along the in-plane direction. The pillar diameter was about 250 nm, and the layered nanostructure was clear, with each layer in the pillar array being < 30 nm. The properties of the oriented (Bi0.5Sb0.5)(2)Te-3 pillar array were greatly enhanced in comparison with those of ordinary polycrystalline films synthesized at deposition temperature of 350A degrees C and 250A degrees C. The (Bi0.5Sb0.5)(2)Te-3 pillar array film with (0 1 5) preferred orientation exhibited a thermoelectric dimensionless figure of merit of ZT = 1.25 at room temperature. The unique pillar array with nanolayered structure is the main reason for the observed improvement in the properties of the (Bi0.5Sb0.5)(2)Te-3 film.